This invention relates to pipe couplings and, more particularly, to an improved method for forming a low pressure pipe coupling and the method of making the improved pipe joint.
There is a continued desire and effort to reduce the cost and increase the reliability of pipe joints. Since pipes are joined to other pipes and to pipe fittings, such as elbows, tees, etc., it is both practically and economically desirable to utilize a joint of common physical configuration for both pipe-to-pipe and pipe-to-fitting joints. Many joint failures presently occur due to two primary reasons. In an improperly designed joint employing an elastomeric seal ring, the seal ring often becomes dislodged during insertion of the pipe end into the female member of the joint or socket. To prevent this dislodgement, positive means must be employed to hold the seal ring in place. One common positive means presently employed is to provide a recess or groove into which the seal ring is fitted; however, these grooves are usually formed by machining or through the use of heat forming. Both of these methods increase the manufacturing costs and tooling costs. A second cause for joint failure, particularly in certain environments such as laying sewer pipes in earthen trenches, is the relatively common occurrence of a rigid member, (for example, sand or pebbles) becoming lodged between the elastomeric seal and the outer shell of the socket creating open leakage paths around the seal ring.
Accordingly, it is an objective of this invention to provide a new and improved pipe joint suitable for use on the end of a pipe for a pipe-to-pipe joint and on a pipe fitting for a pipe-to-fitting joint and which can be economically manufactured and assembled.
It is a further objective of this invention to provide an improved and relatively inexpensive method for making a pipe joint which provides a reliable low pressure seal and which is suitable for use in forming a joint on a pipe end or on a fitting.
Additional objectives and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.